CN118638010A - A method for preparing perfluoroester from fluoroformate - Google Patents

Abstract

The invention relates to the technical field of fluorine chemical industry, in particular to a method for preparing perfluoroester from fluoroformate, wherein fluoroformate and perfluoroolefin in an equal molar ratio are used as reaction raw materials, hydrofluoroether is used as solvent, and bromine organic salt or iodine organic salt is used as catalyst, and the perfluoroester is obtained by reaction in a microchannel reactor; the method for preparing perfluoroester provided by the invention uses hydrofluoroether as solvent and bromine organic salt or iodine organic salt as catalyst, so that the whole system is in liquid phase, no additional metal elements are introduced, the sizes of bromine atoms and iodine atoms are larger, the formed carbon anion intermediate is unstable, which is conducive to the departure of bromide ions/iodide ions, no overreaction occurs, and the generated by-products such as hexafluoropropylene polymers are significantly reduced.

Description

A method for preparing perfluoroester from fluoroformate

Technical Field

The invention relates to the technical field of fluorine chemical industry, in particular to a method for preparing perfluoroester from fluoroformate.

Background Art

Fluoroformate substances are a kind of methylating reagent synthesized from carbonyl fluoride and alcohol substances under the condition of excess carbonyl fluoride. They can be used to synthesize products such as hydrofluoroether perfluoroisopropyl methyl ether (HFE-i7100) and perfluoroisobutyl methyl ether.

However, due to the presence of acyl fluoride functional groups, fluoroformates can also undergo addition reactions to synthesize longer-chain perfluoroalkyl carboxylates, which can also be used to synthesize low-GWP electrical insulating gas perfluoroisobutyronitrile. The method of obtaining long-chain esters using fluoroformate addition has the advantages of more flexible raw material selection, higher reaction activity, fewer by-products and higher atomic utilization. However, research on this reaction has been limited to theory and small-scale synthesis, and its industrialization still faces great difficulties.

In the prior art, an article (Journal of Fluorine Chemistry, 56 (1992) 93-99) mentioned that, in terms of mechanism, fluoroformic acid esters can react with hexafluoropropylene to synthesize perfluoroisobutyrate substances, but no industrializable synthesis process or method was proposed. The catalyst used was also conventional sodium fluoride, and the reaction was a heterogeneous solid-liquid reaction. Under this system, the reaction time was as long as 6 hours, which could not be industrialized. Under this condition, fluoride salt catalysis would cause hexafluoropropylene to self-polymerize and produce hexafluoropropylene polymers, which had a boiling point close to that of related esters and were difficult to separate.

Chinese patent document CN 108395382 A (application number 201810233636.9) discloses a method for synthesizing heptafluoroisobutyrate by reacting chloroformate with hexafluoropropylene in a non-protonic solvent and fluoride salt in one pot. Similarly, it selects fluoride salt as a catalyst, which is very easy to generate hexafluoropropylene self-polymer. The bigger problem is that chloroformate is used as a raw material. The chlorine element in the substance cannot be used to form heptafluoroisobutyrate, which will lead to the formation of chloride salt as a byproduct. The fluoride salt in the system is converted from a catalyst to a raw material, resulting in a large amount of consumption.

It can be seen that although some technologies have mentioned the addition synthesis mechanism of perfluoroesters, fluoride salts are generally used as catalysts. Among them, inorganic fluoride salts have extremely low solubility in organic solvents; while organic fluoride salts are too active, resulting in more by-products. At the same time, the reaction unit generally chooses a reactor, and the reaction form carried out in the reactor is a liquid film reaction. The reaction liquid film selected from the reactor has a small specific surface area and low reaction efficiency, which is not conducive to industrial production. If non-fluoroformate raw materials are used, the atoms cannot be fully utilized, which will cause the fluoride salt to be consumed as a raw material instead of a catalyst.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a method for preparing perfluoroesters from fluoroformates. By using bromine/iodine organic salts as catalysts and hydrofluoroethers as solvents, the reaction is carried out under full liquid phase conditions in a microchannel reactor, effectively improving the selectivity and conversion rate while effectively controlling the reaction time and the output of hazardous waste.

In order to achieve the above technical effects, the present invention adopts the following technical solutions:

A method for preparing perfluoroester from fluoroformate, comprising: using fluoroformate and perfluoroolefin in an equal molar ratio as reaction raw materials, using hydrofluoroether as solvent, using bromine organic salt or iodine organic salt as catalyst, and reacting in a microchannel reactor to obtain perfluoroester;

The method specifically comprises the following steps:

S1. Put the catalyst into the solvent and preheat to obtain a mixed solution for standby use;

S2. The reaction raw materials and the mixed solution are injected into a microchannel reactor together, and the perfluoroester is obtained by distillation and separation after the reaction.

The method for preparing perfluoroester provided by the present invention uses hydrofluoroether as a solvent and a bromine-based organic salt or an iodine-based organic salt as a catalyst, so that the entire system is in a liquid phase, no additional metal elements are introduced, the sizes of bromine atoms and iodine atoms are larger, the formed carbon anion intermediates are unstable, which is conducive to the departure of bromide ions/iodide ions, no overreaction occurs, and the generated by-products such as hexafluoropropylene polymers are significantly reduced.

At the same time, by combining bromine organic salt or iodine organic salt with hydrofluoroether, hydrofluoroether has fluorine-loving chain and ester-loving chain, so that the catalyst and reaction raw materials are dissolved in the solvent, and a homogeneous system is formed at the reaction temperature, which is convenient for reacting in the microchannel reactor to obtain the product. The product output by the microchannel reactor is also in liquid phase. After the product is separated by distillation, the solvent hydrofluoroether can also be separated from the catalyst and by-products at the same time, so that the solvent can be regenerated and reused.

Preferably, in step S1, the mass ratio of the catalyst to the solvent is (5-50):100; further preferably, the mass ratio of the catalyst to the solvent is (5-15):100.

Preferably, in step S2, the mass ratio of the reaction raw material to the mixed solution is 1:(10-50); further preferably, the mass ratio of the reaction raw material to the mixed solution is 1:(20-30).

Preferably, in step S2, the reaction temperature is 30°C-100°C.

Preferably, the fluoroformate is selected from methyl fluoroformate or ethyl fluoroformate, and the perfluoroolefin is selected from hexafluoropropylene or octafluoro-1-butene; further preferably, the perfluoroolefin is octafluoro-1-butene.

Preferably, the catalyst is selected from at least one of tetrabutylammonium bromide, tetrabutylammonium iodide, tetrapropylammonium bromide, tetrapropylammonium iodide, n-butyltriphenylphosphine bromide, n-butyltriphenylphosphine iodide, tetrabutylphosphine bromide or tetrabutylphosphine iodide; further preferably, the catalyst is selected from at least one of n-butyltriphenylphosphine bromide, n-butyltriphenylphosphine iodide, tetrabutylphosphine bromide or tetrabutylphosphine iodide.

When an organic phosphine salt is used as the catalyst, the substance has a higher boiling point, better stability at high temperatures, and higher solubility in hydrofluoroethers.

Preferably, the hydrofluoroether is selected from

CF ₃ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₃ ,

CF ₃ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₂ CH ₃ ,

CF ₃ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₃ ,

CF ₃ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₂ CH ₃ ,

CF ₃ CF ₂ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₃ or

At least one of CF ₃ CF ₂ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₂ CH ₃ .

The above hydrofluoroethers all have relatively long main carbon chains and boiling points above 150°C, and can remain stably in liquid phase under high temperature reaction conditions. However, the commonly used low-boiling-point hydrofluoroethers such as HFE-7100 and HFE-7300 will vaporize at around 50°C and cannot maintain the overall liquid phase of the system during the reaction.

By using hydrofluoroether as a solvent, the reaction system is homogeneous at any time. The solubility of hydrofluoroether can be combined with a certain pressure to prevent it from being significantly vaporized during the reaction, thus avoiding the formation of a plug flow in the microchannel reactor. Since there are no conditions for the formation of solid materials, the entire microchannel reactor is in liquid phase. Compared with fixed-bed catalytic gas phase reactions, it has the advantages of better heat transfer performance, lower reaction temperature, convenient replacement of catalysts and solvents, and no coking, making it more suitable for industrial production.

Preferably, the microchannel reactor comprises a premixer and a reaction channel, and the premixer is used to mix the injected fluid.

The beneficial effects of the present invention are as follows:

The method provided by the present invention ensures that no solid exists or is generated in the whole system by selecting bromine-based organic salt or iodine-based organic salt as a catalyst and hydrofluoroether as a solvent, thereby reducing the operation and maintenance requirements of the microchannel reactor during use, and the solvent can be regenerated by distillation after the reaction has been running for a long time. In addition, the feed does not contain metal elements, and the reaction residue can be completely converted by simple treatment, which reduces the burden of subsequent treatment and reduces the amount of solid hazardous waste generated.

DETAILED DESCRIPTION

The present invention will be further described below with reference to the embodiments and comparative examples.

The raw materials and devices used in each embodiment and comparative example are all commonly used commercially available raw materials and devices in the art. For example, the microchannel reactor can use the microchannel reactor with a premixer provided in Chinese patent document CN 114130326 A (application number 202111516043.1). Those skilled in the art can choose other microchannel reactors with premixers according to actual needs in specific applications. The specific sources of other raw materials are not repeated here.

Example 1

The method for preparing methyl perfluoroisobutyrate from methyl fluoroformate comprises the following specific steps:

(1) First, mix equal volumes of CF ₃ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₃ and CF ₃ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₂ CH ₃ , then add equal mass ratios of tetrapropylammonium bromide and tetrabutylammonium iodide thereto to prepare a mixed solution with a catalyst to solvent mass ratio of 5:100, and heat the liquid to 60°C for standby use;

(2) A mixed solution and methyl fluoroformate and hexafluoropropylene in equal molar ratios were introduced into the inlet of a microchannel premixer with a channel equivalent diameter of 100 μm and a total length of 30 m in the main reaction zone. The total length of the premixer was 0.5 m, the mass feed ratio of the raw material to the mixed solution was 1:50, the flow rate of the mixed material was 1 m/min, and the reaction temperature was controlled at 30 °C;

(3) After distillation, methyl perfluoroisobutyrate with a purity of 99.5% was obtained, with a reaction selectivity of 89.7% and a conversion rate of 82.1%. The structural characterization data of the product are as follows: ¹ H NMR (600 MHz, CDCl ₃ )δ3.89(s, 3H); ¹⁹ F NMR(600 MHz, CDCl ₃ )δ-76.15～-76.17(d, J＝12 Hz, 6H), -183.02～-183.11(m, J＝54 Hz, 1H).

Example 2

The method for preparing ethyl perfluoroisobutyrate from ethyl fluoroformate, the specific steps are as follows:

(1) Add n-butyltriphenylphosphine bromide and n-butyltriphenylphosphine iodide _in equal weight ratio to CF ₃ CF ₂ OCF(CF ₃ )CF ₂ OCF( _{CF 3 )} CF ₂ OCH ₃ to prepare a mixed solution with a catalyst to solvent weight ratio of 50:100, and heat the liquid to 100°C for standby use;

(2) A mixed solution and ethyl fluoroformate and hexafluoropropylene in equal molar ratios were introduced into the inlet of a microchannel premixer with a channel equivalent diameter of 100 μm and a total length of 25 m in the main reaction zone. The total length of the premixer was 0.5 m. The mass feed ratio of the raw material to the mixed solution was 1:30. The flow rate of the mixed material was 1 m/min, and the reaction temperature was controlled at 100 °C.

(3) After distillation, ethyl perfluoroisobutyrate with a purity of 99.3% was obtained, with a reaction selectivity of 91.5% and a conversion rate of 90.9%. The structural characterization data of the product are as follows: ¹ H NMR (600 MHz, CDCl ₃ )δ4.53～4.48 (m, 2H), 1.42～1.38 (t, 3H); ¹⁹ F NMR (600 MHz, CDCl ₃ )δ -76.44～-76.46 (d, J＝12Hz, 6F), -183.17～-183.26 (m, 1F).

Example 3

The method for preparing ethyl perfluoroisovalerate from ethyl fluoroformate, the specific steps are as follows:

(1) Add catalyst tetrabutylphosphine bromide to CF ₃ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ O-CH ₂ CH ₃ to prepare a mixed solution with a mass ratio of catalyst to solvent of 15:100, and preheat the liquid to 80°C for use;

(2) A mixed solution and ethyl fluoroformate and octafluoro-1-butene in equal molar ratios were introduced into the inlet of a microchannel premixer with a channel equivalent diameter of 100 μm and a total length of 25 m in the main reaction zone. The total length of the premixer was 0.5 m, the mass feed ratio of the raw material to the mixed solution was 1:20, the flow rate of the mixed material was 1 m/min, and the reaction temperature was controlled at 70 °C;

(3) After distillation, ethyl perfluoroisovalerate with a purity of 99.4% was obtained, with a reaction selectivity of 91.0% and a conversion rate of 88.8%. The structural characterization data of the product are as follows: ¹ H NMR (600 MHz, CDCl ₃ )δ3.79~3.74 (m, 2H), 1.28~1.26 (t, 3H); ¹⁹ F NMR (600 MHz, CDCl ₃ )δ -70.78～-70.81 (m, 3F), -80.79～-80.81 (m, 3F), -86.26～-86.29 (m, 2F), -118.78～-118.81 (m, 2F), -182.39～-182.48 (m, 1F). After 10 days of continuous operation, the reaction selectivity and conversion rate of the product were able to maintain the initial level.

Example 4

The method for preparing methyl perfluoroisovalerate from methyl fluoroformate comprises the following steps:

(1) Mix equal volumes of CF ₃ CF ₂ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₃ and CF ₃ CF ₂ CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCF(CF ₃ )CF ₂ OCH ₂ CH ₃ , then add catalyst tetrabutylphosphine iodide to prepare a mixed solution with a mass ratio of catalyst to solvent of 50:100, and preheat the liquid to 50°C for use;

(2) A mixed solution and methyl fluoroformate and octafluoro-1-butene in equal molar ratios were introduced into the inlet of a microchannel premixer with a channel equivalent diameter of 100 μm and a total length of 30 m in the main reaction zone. The total length of the premixer was 0.5 m, the mass feed ratio of the raw material to the mixed solution was 1:10, the flow rate of the mixed material was 1 m/min, and the reaction temperature was controlled at 50 °C;

(3) After distillation, methyl perfluoroisovalerate with a purity of 99.4% was obtained, with a reaction selectivity of 90.2% and a conversion rate of 85.0%. The structural characterization data of the product are as follows: ¹ H NMR (600 MHz, CDCl ₃ )δ3.41(s, 3H); ¹⁹ F NMR (600 MHz, CDCl ₃ )δ -70.79～-70.81(m, 3F), -80.78～-80.80(m, 3F), -86.26～-86.29(m, 2F), -118.77～-118.80(m, 2F), -182.39～-182.48(m, 1F).

Comparative Example 1

The method for preparing methyl perfluoroisobutyrate from methyl fluoroformate is as follows:

A 100L reactor was used as the reaction equipment, 200g of 2-perfluorobutylbenzothiazole was added thereto as a catalyst, then 70L of diethylene glycol dimethyl ether solution was added, and finally 312g of methyl fluoroformate and 600g of hexafluoropropylene were added, the reactor was heated at 100°C to a maximum pressure of 1MPa, and the reaction was carried out for 3h. After distillation, methyl perfluoroisobutyrate was obtained with a purity of 99.1%, a reaction selectivity of 87.5%, and a conversion rate of 78.0%. The reaction selectivity, conversion rate, and reaction time were significantly insufficient compared with the embodiments. It should be noted that the system requires high temperature reaction, does not react at 30°C, and cannot obtain the target product.

Comparative Example 2

The method for preparing ethyl perfluoroisobutyrate from ethyl fluoroformate is as follows:

With 50L reactor as reaction equipment, cesium fluoride 200g is added thereto as catalyst, then 156g of ethyl fluoroformate and 300g of hexafluoropropylene are put into, added into 25L ethylene glycol dimethyl ether solution, heated at 150°C, reacted for 6h, and 99.2% purity of ethyl perfluoroisobutyrate product is obtained after rectification, with selectivity of 88.7% and conversion rate of 77.5%. Reaction selectivity, conversion rate, production capacity and reaction time are all significantly insufficient compared with the embodiment. The main impurity generated is hexafluoropropylene dimer, and due to the excessive loss of hexafluoropropylene, ethyl fluoroformate cannot be fully reacted, and the conversion rate decreases.

Comparative Example 3

The method for preparing ethyl perfluoroisovalerate from ethyl fluoroformate, the specific method is as follows:

The reaction equipment is a tube-type fixed bed reactor with a length of 80 cm and a diameter of 2.5 cm and a total volume of 30 L. The catalyst is a mixture of equal masses of aluminum fluoride and potassium fluoride. All pipes are filled and heated to 190 ° C. Ethyl fluoroformate and octafluoro-1-butene are added together in equal molar ratios. The residence time is maintained for 3 minutes. When the reaction starts, the product perfluoroisovalerate ethyl ester has a purity of 99.3%, a selectivity of 90.2%, and a conversion rate of 70.1%. After 10 days of operation, the selectivity dropped to 88.1% and the conversion rate dropped to 65%. With the extension of the operating time, the selectivity and conversion rate have been on a downward trend. After disassembling the reactor, it was found that coking was difficult to clean and replace, which is also the main factor leading to the decline in catalytic activity.

Comparative Example 4

The method for preparing methyl perfluoroisovalerate from methyl fluoroformate is as follows:

A 100L spray tower is used as the reaction equipment, 200g of tetrabutylphosphine iodide is added thereto as a catalyst, and then 312g of methyl fluoroformate and 800g of octafluoro-1-butene are added, and added into a mixed solution of 50L of tetraethylene glycol dimethyl ether, 0.5LCF3CF2CF2O _- CF _{( CF3} ) _CF2OCF ( _CF3 )CF2OCF( _CF3 ) _CF2OCF ( _CF3 ) _CF2OCH3 and _{0.5LCF3CF2CF2OCF} ( _CF3 ) _CF2OCF ( _CF3 ) _CF2OCF ( _{CF3 )} CF2O-CF _{( CF3} ) _CF2OCH2CH3 , heated at 90° _C , the maximum reaction pressure reaches 1MPa, the reaction is carried out for 4h, _and after distillation, 99% purity of methyl perfluoroisovalerate product is obtained, the selectivity is 87.7%, and the conversion rate is 80.1%. Comparative Example 4 uses the same catalyst and reaction system as Example 4, and the conversion rate is significantly improved compared with other comparative examples. However, due to the large gas phase space of the reactor and the large equipment size, the amplification effect is obvious compared with the microchannel reactor under the same conditions, there is a safety risk, and it is not suitable for industrial-scale production.

Comparative Example 5

The method for preparing methyl perfluoroisobutyrate from methyl fluoroformate is different from that in Example 1 in that, in step (1), an equal amount of tetrapropylammonium fluoride is used as the catalyst instead of tetrapropylammonium bromide and tetrabutylammonium iodide, and the other conditions are the same as those in Example 1.

After distillation, methyl perfluoroisobutyrate was obtained with a purity of 99.4%, a reaction selectivity of 82.1%, and a conversion rate of 75.5%. The conversion rate was significantly lower than that in Example 1 because more hexafluoropropylene diaddition by-products were produced when an organic fluoride salt was used as a catalyst.

Comparative Example 6

The method for preparing methyl perfluoroisobutyrate from methyl fluoroformate is different from that in Example 1 in that, in step (1), an equal amount of tetraethylene glycol dimethyl ether is used as the solvent instead of _CF3OCF ( _CF3 ) _CF2OCF (CF3) _CF2OCF ( _CF3 ) _CF2OCH3 and _CF3OCF ( _CF3 ) _CF2OCF ( _CF3 ) _CF2OCF ( _CF3 ) _CF2OCF ( _CF3 ) _CF2OCH2CH3 ; other conditions are the same as _those in Example ₁ .

After distillation, methyl perfluoroisobutyrate was obtained with a purity of 99.1%, a reaction selectivity of 83.5%, and a conversion rate of 70.1%. This is because the solvent did not use hydrofluoroether, which could not ensure that the reaction system always remained in a full liquid phase state, resulting in significant plug flow during the reaction, which in turn caused a serious decrease in the conversion rate.

Claims (10)

1. A method for preparing perfluorinated acid ester by using chlorofluoro ester is characterized in that the perfluorinated acid ester is prepared by reacting in a micro-channel reactor by taking chlorofluoro ester and perfluorinated olefin in an equimolar ratio as reaction raw materials, hydrofluoroether as a solvent and bromine-based organic salt or iodine-based organic salt as a catalyst;

the method specifically comprises the following steps:

s1, putting a catalyst into a solvent, and preheating to obtain a mixed solution for standby;

s2, injecting the reaction raw materials and the mixed solution into a micro-channel reactor together, reacting, rectifying and separating to obtain the perfluorinated acid ester.

2. The method for producing a perfluoroacid ester from a chloroformate according to claim 1, wherein the mass ratio of the catalyst to the solvent in step S1 is (5-50): 100.

3. The method for producing a perfluoroacid ester from a chloroformate according to claim 2, wherein the mass ratio of the catalyst to the solvent in the step S1 is (5-15): 100.

4. The method for producing a perfluoroacid ester from a chlorofluoro acid ester according to claim 1, wherein in step S2, the ratio by mass of the reaction raw material to the mixed solution is 1 (10-50).

5. The method for producing a perfluoroacid ester from a chlorofluoro acid ester according to claim 4, wherein in step S2, the ratio by mass of the reaction raw material to the mixed solution is 1 (20-30).

6. The method for preparing a perfluoroacid ester from a chloroformate according to claim 1, wherein the reaction temperature in step S2 is 30 ℃ to 100 ℃.

7. The process for preparing a perfluoroacid ester from a chloroformate according to claim 1, wherein the chloroformate is selected from methyl chloroformate or ethyl chloroformate and the perfluoroolefin is selected from hexafluoropropylene or octafluoro-1-butene.

8. The method for preparing a perfluoroacid ester from a chloroformate according to claim 1, wherein the catalyst is at least one selected from the group consisting of tetrabutylammonium bromide, tetrabutylammonium iodide, tetrapropylammonium bromide, tetrapropylammonium iodide, n-butyltriphenylphosphine bromide, n-butyltriphenylphosphine iodide, tetrabutylphosphine bromide and tetrabutylphosphine iodide.

9. The method for preparing a perfluoroacid ester from a chloroformate according to claim 1, wherein the hydrofluoroether is selected from the group consisting of

CF₃OCF(CF₃)CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCH₃、

CF₃OCF(CF₃)CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCH₂CH₃、

CF₃CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCH₃、

CF₃CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCH₂CH₃、

CF₃CF₂CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCH₃ Or (b)

CF₃CF₂CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCF(CF₃)CF₂OCH₂CH₃ At least one of them.

10. The method of preparing a perfluoroacid ester according to claim 1, wherein the microchannel reactor comprises a premixer and a reaction channel, the premixer being configured to mix the injected fluid.